Means and method of tilting explosive charges in wells



March 6, 1951 w. H. THoMPsoN ETAL 2,543,814

MEANS AND METHOD oF TILTING EXPLOSIVE CHARGES IN WELLS Filed Dec. 26,1946 I--zr Fig. 3

'Patented Mar. 6, 1951 MEANS AND METHOD F TILTING ExrLosIvE CHARGES 1NWELLS Willis H. Thompson, Eugene 0.

Tolson, and Rob:

ert H. McLemore, Fort Worth, Tex., assignors to Welex Jet Services, acorporation of Texas Application December 26, 194s, serial-No. 718,372

The invention relates to a means and method of shooting .wells in whichor tubingis employed.

It is well known to shoot wells with charges of.

explosives and lmore recently with lined shaped high explosive chargesin order to obtain a maximum of penetration in either the open well bore.or through the casing, cement, and into the formation therearound.

The present invention, however, directs itself to an arrangement wherebyshaped lined high explosive charges can be lowered into a well bore`through a small dlameterpipe or tubing and then tilted into detonatingposition in order to `get the maximum penetration.

Another object of the invention is to provide an assembly for shootingwells whichis made up of a string or support member carrying one or moreexplosive charges which can tilt to ahorizontal position after havingbeen lowered into the well bore through a small diameter pipe. 1

Another object of the invention is to provide a means and method ofshooting wells drilled by the rotary method, after setting the casing,lowering the tubing and washing the well,

Still another object of the invention is to lower one or more explosivecharges through a tubing into a well bore for shooting the well wherethe charge is of greater length than the diameter of the tubing.

Still another object of the invention is to provide a combination of asupporting memberand a shaped lined explosive charge which is pivotallymounted therein so as to tilt to detonating position after the chargehas been lowered through the tubing in the well therebelow.

Other and further objects of the invention will be readily apparent whenthe following description is considered in connection with theaccompanying drawings, wherein:

Fig. 1 is a side elevation of a well bore equipped with a cementedcasing and tubing and illustrating a string of explosive charges as inthe process of being lowered 'into detonating position.

Fig. 2 is an enlarged view of one of the charges which is of greaterlength than the diameter of the tubing shown in tilted position whilepassing downwardly through the tubing.

Fig. 3 is an enlarged view with certain parts in section illustratingone of the cartridges which has tilted by gravity to detonatingposition.

In Fig. 1 the well bore 2 has been drilled by the rotary method ofdrilling, where a drill bit and drill pipe are rotated while beinglowered into the earth. A drilling fluid or mud is cir- 6 Claims. (Cl.102--20ll aismall diameter pipe Inc., Fort Worth, Tex.,

2 culated down through the drill pipe and discharged from the drill bitto move upwardly in the well bore for the purpose of, carrying away `thecuttings from the bit, supporting the wall of the well, and maintaininga predominate pressure upon the earth formations to holdback anypressures encountered therein.

When the drilling of the well is completed, it is usual to run a surveyof the well for the purposes of locating porous formations in which itis believed that gas or oil will be encountered. The surveys indicatethe elevation of such formations and such surveys are considered asstandard practice.

After the survey has been made, the usual procedure is to run a stringof large diameter pipe or casingr 3 which substantially fills the wellbore 2.

This pipe is usually extended to the bottom of the well bore and say forinstance the formation 5 is` a productive formationfrom which it isdesired to obtain production, Vsuch formation will be closed off by thecasing and in order to anchor the casing securely in position, cement ispumped downwardly through the casing, upwardly around the lower endthereof, and is seen at 6 as llling the space between the casing and thewell bore.

The casing and the cementing are both accomplished While the heavyvdrilling mud remains in position so as to prevent any gas pressure inthe formation 5 from blowing into the well.

The usual practice as now conducted is to then lower the perforating guninto the well and discharge bullets laterally of the casing in an eortto penetrate the casing and the cement opposite the formation 5 asindicated by the survey so as to form openings in the pipe to admitfluid to the well. When such an operation is performed, the heavydrilling mud usually penetrates the openings and oftentimes muds off theporous formation 5 and prevents the entrance of the production liquid.

The present invention contemplates a procedure whereby the perforatingoperation is deferred until after the tubing 8 has been lowered intoposition and the well head and other equipment aiiixed at the surface.Ihek gungfperforatlng operation is performed with thetdrillingmud inplace because the pressure of vthedrilling'-mud is required to hold backthe formation pressure until the perforating gun can be removed from`the well. The present invention contemplates an arrangement whereby thetubing will be run into place and the well head equipment alxed and thenthe heavy drilling mud washed fromv the well prior to the time ofDerforating the casing.

Fig. 1 shows the well as having been thus washed with a liquid of lesserspecific gravity than the drilling mud, and as a matter of fact, aliquid is usually employed which will apply a pressure against theproducing formation 5 which is less than the pressure in the formation.

After the well has been washed as described, the explosive assembly Iwill then be lowered through the tubing 8 into the well. This assemblyI0 is made up of a string or support member I2 which may be of anysuitable material such as scrap iron, plastic or other material whichwill support a plurality f explosive cartridges I3. The weight of thesecartridges is usually but a few ounces and it is evident therefore thatalmost any type of material will be suitable for the string I2. 'I'hisstring I2 may terminate a short distance above the uppermost cartridgeand the weight of the entire assembly thus carried by suitable meanssuch as a conductor cable I4 which will carry a current oi' electricityfor detonating the explosive cartridges.

A particular feature of this assembly is best illustrated at the secondcartridge from the top in Fig. 1, where the support member is shown asdivided into the straps I5 and I6 which are spaced apart for a distancesuicient to receive the cartridge I3 therebetween. Suitable pivotsupports I1 on each side of the cartridge and the straps serves toretain the cartridge in pivotal position so that it may be tilted towardthe vertical as seen in the upper part of Fig. 1. Such an arrangement isdesirable because of the fact that the length of the cartridges I3 isgreater than the internal diameter of the tubing 8 and tilting of thecartridge therefore permits it to be lowered Y through the tubing.

While a single ended shaped lined explosive charge has been illustrated,it is obvious that a double ended charge may be employed. It should benoted that for eifective penetration with a shaped lined charge, thereshould be preferably provided a stand-off distance or space at the mouthof the cone which is of suilicient width to the closure of the charge soas to permit collapse of the cone upon detonation. Various factorsaffect and determine this stand-olf distance but in actual practice intest shots, it has been found generally that the foregoing is true. Therelative dimensions of the cartridges are xed to a substantial extentdue to the arrangement of the explosive charge 20. As seen in Fig. 3 theshaped cavity, the liner 22 therefor, and the closure end 23 must comewithin certain requirements relating to shaped lined closed highexplosive cartridges. A description of a general nature of such acartridge is to be found in the Australian Patent 113,685 acceptedAugust 14, 1941 in Class 89.9 to Sabeg. There are certain ratios oflength to diameter of the explosive charges which permit the detonationwave to atten suiciently by the time it contacts the apex of the cone orliner 22 which is deposited in the shaped area 2|. The space inside ofthe end 23 must be suicient to allow collapse of the liner and for suchliner to act as a projectile and attain its velocity before penetratingthe closed end 23. It has been found, therefore, that the length of acharge having sufiicient ability to penetrate the casing and cementtherearound, in all probabilities exceeds the usual internal diameter ofthe tubing and the provision for the tilting of the cartridges hastherefore been made.

band or ring 25 of lead or other relatively heavy material will beapplied so that the tendency for the cartridge is to tilt to thehorizontal position. 0f course the pivot I1 can be arrangedlongitudinally of the cartridge so that it will tilt by gravity with thering 25.

In order to check the tilting movement of the cartridge and stop it in asubstantially horizontal position, any suitable means may be provided. Acheck string 21 is shown in Fig. 3.

The conductor cable I4 may be arranged along the support member I2 inany suitable diameter solong as it is capable of extending at 29 to thedetonator 30 arranged in the base of the cartridge I 3. The sameconductor extends to all of the cartridges. While the mechanism has beenshown as being detonated by electricity, .it seems.

obvious that any suitable method could be used to eiect detonatlon ofthe mechanism either in series, or simultaneously as a unit.

A particular advantage of the present arrangement is the manner in whichthe entire assembly I II will be consumed by the explosion and little orno foreign material will remain in the well bore after the shootingoperation. Only the cable I4 need then be removed. Such a cable can bereadily sealed at the surface and it seems obvious that each of thecharges will tilt to its horizontal position as it passes through thelower end of the tubing.

Broadly the invention contemplates a means and method of lowering spacedcharges through a small diameter pipe or tubing into a well bore toshoot the well and also to a method of completing wells by perforatingthe well after the well has been washed.

What is claimed is:

1. An assembly for shooting wells comprising a support member, aplurality of cylindrical explosive cartridges, and means connecting saidcartridges to said member to allow tilting of the cartridges fromvertical to horizontal position, each cartridge including a closed,lined shaped charge of high explosive.

2. An assembly for shooting wells comprising a support member, aplurality of cylindrical explosive cartridges, means connecting saidcartridges to said member to allow tilting of the cartridges fromvertical to horizontal position, each cartridge including a closed,lined shaped charge or high explosive, and additional means to detonatesaid cartridges.

3. A device for shooting wells comprising a cylindrical explosivecartridge, means to pivotally support said cartridge by lowering intothe well bore through a pipe of lesser diameter than the length of thecartridge so that the cartridge tilts to a horizontal position as itemerges from the pipe at the area to be shot.

4. A method of shooting wells equipped with a casing and tubing whichcomprises assemblying one or more high explosive cartridges for pivotalmovement upon a support string, lowering the string and cartridgesthrough the tubing so that the cartridges tilt toward a verticalposition while passing through the tubing and tilt toward a horizontalposition as they emerge from the lower end of the tubing into the casingor open well bore, and detonating the cartridges.

5. An assembly for shooting wells comprising a support member, aplurality of cylindrical explosive cartridges, means connecting saidcartridges to said member to allow tilting of the In order to facilitatetilting of the cartridge. a 'l5 cartridges from vertical to horizontalposition,

5 each cartridge including at least one closed. lined shaped charge ofhigh explosive, and additional means to detonate said cartridges.

6. An assembly for shooting wells comprising a support member, aplurality of cylindrical explosive cartridges, and means connecting saidcartridges to said member to allow tilting of the cartridges fromvertical to horizontal position,4

each cartridge being overweighted at one end. WILLIS H. THOMPSON.

EUGENE O. TOLSON. ROBERT H. MCLEMORE.

REFERENCES CITED The following references are of record in the ille ofthis patent:

Number 6 UNITED STATES PATENTS Name Date Church Oct. 8, 1935 Wells Mar.10, 1936 Morriss Jan. 12, 1937 Ennis Jan. 14, 1941 Croft Jan. 21, 1941Smith Mar. 13, 1945 Alexander Dec. 11, 1945 Davis Apr. 30, 1946McWhorter Aug. 26, 1947

